Coupling for connecting vacuum-insulated line ends

ABSTRACT

The invention relates to a coupling for connecting vacuum-insulated line ends via a coupling socket and a coupling plug which are provided for conveying a cryogenic medium and which have closing elements at the outer line ends that close the line ends. So that the valve-like means can be opened or closed by remote control in a defined manner, the coupling plug (10) has a control unit (43) that is connected to the closing element (29) and that opens at least the closing element (29) when exposed to control pressure.

BACKGROUND OF THE INVENTION

This application is related to DE 197 27 655.5 filed on Jun. 30, 1997,which is incorporated by reference in its entirety for all purposes.

The invention relates to a coupling for connecting vacuum-insulated lineends via a coupling socket and a coupling plug which are provided forconveying a cryogenic medium and which have means at the outer line endsthat close the line ends.

Couplings for cryogenic media are already known which can be dividedinto two groups on the basis of their connection mechanism and theirmeans for opening and closing the line ends.

DE 19516029 C1, DE 4041337 A1 and DE 4339676 A1 disclose couplings forcryogenic media which have a coupling plug and a coupling socket. Thecoupling plug is inserted into the coupling socket so that the outervacuum-insulated outer coupling housings overlap and a connectionelement arranged on the outside of the coupling housing can be engagedwith a counterpart arranged on the coupling plug. The connection isestablished by screwing the coupling plug to the coupling socket. Duringthe performed process of sliding the coupling plug into the couplingsocket, the coupling is first sealed off against the ambient medium;then the means that close the line ends are opened. The valve-like meansin this embodiment of the coupling are located far away from theseparation plane inside the coupling socket in the coupling plane.

In the separation plane, the outer faces of the coupling plug and thecoupling socket are directly across from each other.

In the coupling plane, the means that close the line ends are directlyacross from each other. The means can be opened or closed and, when themeans are opened, cryogenic medium can flow from the line end of thecoupling plug to the line end of the coupling socket.

Moreover, DE 4104711 A1 and U.S. Pat. No. 4,335,747 A1 disclose thetechnique of sealing against ambient medium separately from theopening/closing of the means directly adjacent to the separation planeby means of ball valves. The connection of the coupling plug with thecoupling socket is established with mechanical elements in theseparation plane. Likewise far away from the separation plane, in thecoupling socket, these couplings have valve-like means whose opening iseffectuated by means of the line end of the coupling plug that can bemechanically slid beyond the separation plane and through the openedball valves all the way to the coupling plane. For this purpose, theline end of the coupling plug is configured to be flexible like acorrugated hose.

From a mechanical and safety-related standpoint, the interlockingscrewed connections of the known couplings for opening the valve-likemeans are not a feasible solution since, for example, a great deal ofmechanical and electrical effort is needed with the automatic rotationof the union nut proposed in DE 40 41 337 A1 and this leads to a set-upthat can no longer be handled by non-technical personnel in terms of thesize and the weight of the coupling. In contrast, the solution proposedin DE 41 04 711 A1, namely, to slide the line end by turning a setscrewuntil the valve-like means opens, leads to a complicated mechanicalconstruction of the means and of the line end ensuring the seal betweenthe coupling plug and the coupling socket. However, the instructionsdisclosed in DE 195 16 029 C1, i.e., to exert the force by means of alever, a cam or a cylinder powered by an outside medium during theplugging and connecting of the coupling plug with the coupling socket,only follows the path indicated by the known state of the art describedabove, namely, to connect the coupling housings to each other by meansof a relative movement. Here, the valve-like means are located far awayfrom the separation plane inside the coupling socket. Theplug-in/push-in connection is unsatisfactory from a safety standpointwhen the coupling socket is located as a refueling device (tank closure)on a vehicle and the coupling plug is located on a pump of a servicestation, since the plug-in connection can cause serious damage to theservice station and/or the vehicle if the vehicle drives away while itis still connected, even if the coupling plug is separated form thecoupling socket in the separation plane and the coupling plug to thecoupling socket is located in the coupling plane. In addition, duringthe refueling of cryofuel tanks of vehicles, lay persons operate thecoupling, which calls for a simple and safe design of the coupling sothat the users do not come into contact with the cryogenic fuel.

Therefore, couplings for cryogenic media would be desirable in which thedisadvantages according to the state of the art are avoided.

SUMMARY OF THE INVENTION

The invention is based on the objective of creating a coupling forcryogenic media with which the valve-like means can be opened or closedby remote control in a defined manner and whereby the operational safetyas well as operating errors are improved in comparison to the prior artcouplings.

This objective is achieved according to the invention by a coupling ofthe type described above having the features of claim 1.

Advantageous embodiments of the invention are described in the dependentclaims.

Due to the remote-controlled activation of the coupling according to theinvention, the flow path of the cryogenic medium is released directly,independent of the plug-in/push-in paths. The detachable and, in case ofemergency, releasable connection of the coupling plug and couplingsocket is carried out previously in a separate step. This ensures thatthe operator of the coupling does not come into contact with thecryogenic medium since he/she only has to establish the connection ofthe coupling plug and coupling socket at the coupling, and the openingof the means takes place away from the coupling via an operatingelement. The opening of the means can also be carried out automaticallyat a prescribed time, e.g. by inserting coins or tokens or by using acredit or debit card.

The control effort is simplified when the means that close the two lineends open in the same direction so that the control unit that is under acontrol pressure, preferably a control gas, slides a control elementbeyond the separation plane, thus opening the two valve-like means.Here, the control element provided for the coupling plug is configuredas a control rod having a gasket that is pulled by means of the force ofa spring element of the bellows against a sealing surface formed at theline end, while the gasket of the coupling socket supported by a closingelement is pressed by the force of a spring element or bellows againstthe sealing surface present on the line end. If the control rod slidesaxially to the coupling socket due to the extending control unit, thegasket lifts the control rod off of the sealing surface; at the sametime, the control rod removes the closing element from the seat againstthe force of the spring element or the spring properties of the bellows,so that the gasket on the closing element is likewise lifted off of thesealing surface and the cryogenic medium can flow from the coupling plugto the coupling socket.

An especially simple control unit has bellows, preferably metal bellows,whose inner chamber is connected to a control line whose other end isconnected to a compressed gas chamber. The control line contains aremote-controlled valve that can be opened or closed via a controlsignal or closed with the simultaneous pressure-relief of the bellows.Of course, the control unit can also be configured as a piston-cylinderunit.

The dimensions of the coupling can be reduced and the mechanicalstructure can be greatly simplified if the control unit is located inthe line end, since passages and connections are dispensed with and themeans can be connected directly to the control unit.

The virtually straight-line sliding of the control rod and of theclosing element is achieved by a centering element that is attached tothe face of the control rod and that engages with a counterpart situatedon the closing element of the coupling socket so as to hold thecentering element in an interlocking manner. The interlocking connectionensures the axial guidance of the control rod which is centered in theguided closing element of the coupling socket.

The coupling can be cooled down when the means are closed by means oftwo lines that are connected to the line end. In this process, the linewith the smaller diameter serves as the filling line through which thecryogenic medium flows into the line end and pre-cools the line end. Theevaporated medium flows through the line with the larger diameter. Whenthe coupling is in operation, the cryogenic medium flows through bothlines so as to be able to achieve the largest possible mass flows andthus a shortening of the filling time with little pressure loss.

The connection of the line ends of the coupling plug and coupling socketis established directly adjacent to the separation plane, since all ofthe means for closing the two line ends are provided directly adjacentto the separation plane, so that the separation plane and the couplingplane lie virtually in the same plane. This facilitates the handling ofthe coupling since plug-in/push-in processes of the stainless-steelcoupling housings are eliminated. The safety is increased since, in caseof error, no interlocking connection holds the coupling plug in thecoupling socket. In addition, all of the gaskets are located detachablydirectly adjacent to the separation plane and are thus readilyaccessible. Therefore, the replacement of defective gaskets can be donein a simple manner.

The sealing of the coupling plug and the coupling socket in theseparation plane preferably takes place via two coupling surfaces oneach of which there is a gasket. The one outer gasket seals the couplinghousing against the penetration of ambient medium and prevents iceformation, whereas the inner gasket seals the means so as to prevent theescape of cryogenic medium. Thanks to the gaskets that form a sealedannular chamber when they are in the coupled state, a link between thewarm ambient medium with the cryogenic medium is prevented.

The connection of the coupling plug with the coupling socket isestablished via a locking element that is supported on the coupling plug(fixed bearing) and that pulls the coupling socket against the couplingsurfaces with the gaskets. For this purpose, the coupling socket has aflange along its circumference behind which a half-shell element of thelocking element grasps and which is pulled to the coupling plug side bymeans of a rod assembly. In this process, the gaskets tightly seal thecoupling surfaces of the coupling plug and the coupling socket. The flowpressure that is established in the line end when the means are openalso brings about pressure-proportional sealing forces on the gasket onthe side of the coupling plug. Advantageously, the locking element isconfigured in such a way that it can immediately be detached by anemergency release, preferably after the internal closing process, sothat the coupling plug and the coupling socket are immediately freelymovable. An embodiment of the emergency release can consist of a ripcord that opens the switch-over lever of the locking element andreleases the rod assembly with the half-shell element when a specifiedtensile force on the coupling is exceeded. Naturally, there are numerousother mechanical, pneumatic, hydraulic electric or magnetic embodimentvariants of an emergency release that the person skilled in the art canprovide, so that the invention is not limited to this embodiment.

Preferably the coupling plug is part of a service station pump and thecoupling socket is provided as a tank closure in a vehicle that isrefueled with a cryofuel.

An embodiment of the invention is shown in the drawing and will bedescribed in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is shown:

FIG. 1 a longitudinal section of a coupling in which the two line endsof the coupling plug and of the coupling socket are closed;

FIG. 2 a schematic representation of the coupling housing coupledtogether with the locking element;

FIG. 3a a schematic longitudinal section of the coupling shown in FIG. 1with an open flow path;

FIG. 3b a schematic longitudinal section of the coupling shown in FIG. 1with a closed flow path;

FIG. 3c a schematic longitudinal section of the coupling shown in FIG. 1with the coupling plug and the coupling socket separated from eachother.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The coupling according to FIG. 1 shown in a longitudinal sectioncomprises a coupling plug 10 and a coupling socket 11 for connecting twoline ends 12, 13 (FIG. 3a). The connection of the coupling plug 10 withthe coupling socket 11 is made by the locking element. For this purpose,on the vacuum-insulated coupling housing 16 of the coupling plug 10,there is a switch-over lever 15 which is supported so that it can rotatearound an axis 21 and on which a rod assembly 17 is supported outside ofthe rotating axis 21 so as to pivot. A half-shell element 18 is attachedto the rod assembly and said half-shell element 18 grasps around aflange 19 of the vacuum-insulated coupling housing 22 of the couplingsocket 11 and, when the switch-over lever 15 rotates around the axis 21,pulls the flange 19 against a flange 20 of the coupling plug. Via themovement of the element 18, the necessary mechanical force is generatedto pull the vacuum housing 22 of the coupling socket 11 against thecoupling surfaces 25, 26 (having the gaskets 23, 24) of the couplingplug 10.

Each coupling housing 16, 22 forms an insulating vacuum chamber thatextends virtually over the entire length of the coupling plug 10 and thecoupling socket 11 to prevent evaporation during the flow of cryogenicmedia in the line ends 12, 13. The line ends 12, 13 extend all the wayto the separation plane 27 of coupling plug 10 and the coupling socket11. At each line end 12, 13, there are means 28, 29 across from eachother (FIG. 3c) and arranged directly adjacent to the separation plane27 for opening and closing the line ends 12, 13. The means 28 of thecoupling socket 11 consist of a closing element 30 that closes the lineend 13 and that has a gasket 31 made of PTFE. The closing element 30 isheld on the sealing surface 33 by means of a spring 32 and underpressure exerted by the medium (FIG. 3b). The sealing surface is locatedinside the expanded line end 13 and configured as a wall of the line end13 tapered at an angle. The closing element 30 with the gasket 31 ispressed by the spring 32 against the sealing surface 33. The closingelement 30 has a recess 34 that is designed as a counterpart to acentering element 35 of the coupling plug 10 and that receives thiscentering element 35 of the coupling plug 10 in an interlocking manner.

The means 29 of the coupling plug 10 for opening and closing the lineend 12 is arranged directly adjacent to the separation plane 27 andconsists of a control rod 36 that has an open recess 37 facing thecoupling side and that has a gasket 38 made of PTFE. The gasket 38 iscovered from the top by a flange 39 of the centering element 35. Thecentering element 35 is connected detachably to the control rod 36 viascrew 40 from the free side of the line end 12. The control rod 36 withthe gasket 38 is pulled by means of the spring 41 against the sealingsurface 42. The sealing surface 42 is provided at the expanded line end12. The control rod 36 is connected to a control unit 43 configured asbellows 44. The control unit has an internal chamber 45 that isconnected via a control line 46 with a pressure chamber (not shownhere). The control fluid of the internal chamber is fed into theinternal chamber 45 through control line 46 by control means (not shownhere).

An element 47, for example, a screw, that limits the stroke of thecontrol rod 36 is screwed into the side of the control rod 36 facing theinternal chamber 45 and is limited by a contact surface 48 that isconnected to the internal chamber, and the passage opening of thecontact surface 48 for the element 47 is smaller than its head 49. Theoutward stroke of the control rod is limited by the screwed-in length.This prevents damage to the bellows 44 if the bellows 44 is put undercontrol pressure in the uncoupled state.

The expanded line end 12 of the coupling plug is connected via two lines50, 51, that essentially run concentrically, with a tank (not shownhere) containing the cryogenic medium.

As FIGS. 3a and 3b show, the two coupling housings 16, 22 are positionedfacing each other in the separation plane 27. Centering rings 52, 53provided on the faces serve for positional orientation. By pushing downthe switch-over lever 15 and the force-boosting mechanism, the couplingplug 10 and the coupling socket 11 are pulled tightly against each otherand locked in position; the inner and outer gaskets 24 and 23 aredeformed. In this position, which is now sealed to the outside, no flowof the cryogenic medium is possible--the dead volume between couplingplug 10 and coupling socket 11 is not pressurized either since it isminimized by the interlocking of the connection surfaces. By applyingthe control pressure, the internal chamber 45 of the bellows 44 ispressurized. The bellows moves the control rod holding the gasket 38perpendicular to the side of the coupling socket beyond the separationplane 27. Consequently, the means 28 of the coupling socket is movedinto the open position together with the means 29 of the couplingsocket. The two line ends 12, 13 are now connected to each other and thecryogenic medium can flow. After the end of the medium flow, theinternal chamber 45 is pressure-relieved via the control line 46. Thespring 41 pushes the control rod 36 with the bellows 44 into the closedposition until the gasket 38 lies tightly against the sealing surface33. This process is assisted by the pressures in both line ends 12, 13since the effective bellows and sealing surfaces generate additionalclosing forces.

The coupling can now be separated by operating the switch-over lever.

What is claimed is:
 1. Coupling for connecting a pair ofvacuum-insulated lines via a coupling socket and a coupling plug whichare provided for conveying a cryogenic medium, the coupling being incombination with the pair of lines, each of the lines has a line end andclosing mean at the line end for closing it, one of the closing means isconnected with a control unit that opens the closing means,characterized in that the coupling plug has first closing means which isconnected to said control unit and has an internal chamber that isconnected to a control line, and the control unit opens the firstclosing means when exposed to a control pressure applied through thecontrol line into said internal chamber.
 2. Coupling according to claim1, characterized in thatthe control unit is configured as a bellows,that has an internal chamber that is connected to a control line. 3.Coupling according to claim 1, characterized in thatthe control unit isarranged in the line end.
 4. Coupling according to claim 1,characterized in that the coupling socket and the coupling plug areseparated by a separation plane, and that the control unit is connectedto a control element of the first closing means and the control unitslides the control element beyond the separation plane, thereby openingthe line ends.
 5. Coupling according to claim 4, characterized inthatthe control element has a control rod that is connected to thecontrol unit and that holds a gasket which lies on a sealing surface bymeans of the force exerted by a biasing element at one line end. 6.Coupling according to claim 5, characterized in thatthe gasket is pulledagainst the sealing surface by means of the spring force from outside ofthe line end.
 7. Coupling according to claim 5, characterized in thatthecontrol rod has a centering element on its side facing the couplingsocket.
 8. Coupling according to claim 5, characterized in thatthe lineend is connected to two lines for filling and/or discharging thecryogenic medium.
 9. Coupling according to claim 5, characterized inthatthe face of the line end facing the coupling socket has at least oneannular coupling surface and at least one gasket is located on thecoupling surface.
 10. Coupling according to claim 1, characterized inthatthe coupling socket has a closing element in the line end, wherebysaid closing element has a gasket that, by means of the force of aspring element, lies against a sealing surface present at the line end.11. Coupling according to claim 10, characterized in thatthe gaskets ispulled against the sealing surface by means of the spring force. 12.Coupling according to claim 10, characterized in thatthe face of theclosing element has a recess to receive the centering element. 13.Coupling according to claim 1, characterized in thatthe means of bothline ends are located directly adjacent to the separation plane of thecoupling socket and of the coupling plug.
 14. Coupling according toclaim 13, characterized in thatthe gaskets of the means and the gasketsfor sealing against the ambient and cryogenic medium are directlyadjacent to the separation plane and are detachable.
 15. Couplingaccording to claim 9, characterized in thatthe connection of thecoupling plug with the coupling socket is established via a lockingelement that is supported on the coupling socket and that pulls thecoupling socket against the coupling surfaces whereby the gaskets lie soas to create a tight seal between the coupling surfaces.
 16. Couplingaccording to claim 15, characterized in thatthe locking element isconfigured in such a way that it can immediately be detached by anemergency release, preferably immediately after the closing process. 17.Coupling plug as part of a service station pump 1 and coupling socket asa tank closure of a vehicle according to claim 1.